Traffic intersection



Sept. 13, 1966 D. c, GAZIS ETAL TRAFFIC INTERSECTION 5 Sheets-Sheet 1 Filed Dec. 9, 1963 FIG. I

INVENTORS DENOS C.GAZ|S RENFREY B. POTTS BY ATTORNEY D. (Z. GAZIS ETAL- TRAFFIC INTERSECTION Sept. 13, 1966 :5 Sheets-Sheet 2 Filed Dec. 9, 1965 V POWER SOUVRCE Sept. 13, 196 D. c. GAZIS ETAL TRAFFIC INTERSECTION 5 Sheets-Sheet 5 Filed Dec. 9, 1963 1ST'MINUTE TIME v 1 2 1 m H mm z mmum FIG. 3

3,272,097 TRAFFIC INTERSECTION Denos C. Gazis, Millwood, N.Y., and Renfrey B. Potts,

Erindale, South Australia, Australia, assignors to International Business Machines Corporation, New York,

N.Y., a corporation of New York Filed Dec. 9, 1963, Ser. No. 322070 Claims. (Cl. 94-1) This invention relates to apparatus and methods for controlling trafiic, and more particularly to traffic intersections.

One reason for congestion on the roadways in cities and in rural areas is the build-up of traflic at oversaturated intersections. Oversaturation occurs whenever a stream of traffic approaching a traffic light becomes heavier than that which can be accommodated by the corresponding green portion of the trafiic light. Various well-known solutions have been employed to relieve the saturated condition. For example, overpasses have been constructed which permit one stream of traffic to pass over the top of the other stream of traffic, thereby permitting two continuous streams of tratfic to move through an intersection without delay. One apparent disadvantage of the overpass is the cost of constructing this type of roadway.

Still another solution to the problem of the oversaturated intersection is the familiar trafiic circle. Here, provided the number of cars entering the circle is not too excessive, traffic continuously moves through the trafiic circle with only the delay caused by the change in direction of the roadway while traveling about the circle. Normally the width of the roadway about the traffic circle is made sufficiently wide to accommodate at least two lanes of trafiic so that vehicles on the circle need not slow down to permit additional vehicles to enter the circle. This creates the problem of lane changing, or lane weaving, since the vehicles on the inner lane of the circle must cross over the outer lane in order to leave the trafiic circle. The weaving is done in an unsupervised manner and safety is made to depend upon the skill and judgment of the individual drivers.

It is an object of the present invention to provide an improved traflic intersection system.

Another object of the present invention is to provide an improved method of passing continuous streams of trafiic through an intersection at the same level without the necessity of an overpass.

It is a further object of the present invention to provide improved apparatus for controlling the flow of continuous streams of traffic through an intersection.

Still another object of the present invention is to provide methods and means for permitting continuous streams of traffic to pass through an intersection without appreciable delay or high cost of installation.

It is a further object of the present invention to provide methods and means for permitting continuous streams of traflic to flow through an intersection without requiring vehicles to change lanes.

These and other objects of the present invention are accomplished by providing a network of roads surrounding four blocks arranged in a matrix, or checkerboard fashion. In this manner four pairs of adjacent roadways are formed along the interior of the matrix. Four crossover points are constructed which permit the tratfic on one roadway of each pair to cross over to the adjacent roadway in the pair, and vice versa.

atent ice Located at the corners of the matrix are traffic controlling devices which divide the incoming streams of trafiic into two platoons. The first platoon of each incoming stream of traffic is directed in a clockwise direction, while the second platoon is directed in a counterclockwise direction around the periphery of the matrix. When the incoming streams of trafiic are divided in this manner no stoppage occurs at the crossover points since the times of arrival of different platoons at the crossover points do not coincide or overlap.

The two platoons from each incoming stream of traflic are reformed at the opposite corner of the matrix into a single stream of outgoing trafiic.

A trafiic intersection constructed in accordance with the present invention has the advantage of low cost since no costly overpass structures or traflic circles need be constructed. Existing city streets or rural highways can be employed with only slight structural modification.

A further feature of the present invention is the absence of any unsupervised lane weaving during the passage through the intersection. Therefore the safety of the passengers is improved.

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawings.

In the drawings:

FIG. 1 is a schematic illustrating a network of roads constructed in accordance with the present invention;

FIG. 2 is an electrical schematic illustrating the manner in which the traffic lights employed in FIG. 1 are operated; and

FIG. 3 is a waveform diagram illustrating the signals applied to the lights in FIG. 2.

FIG. 1 illustrates a network of roads surrounding four blocks 11-14. The blocks are arranged in a matrix, or checkerboard fashion similar to that found in most cities. As shown in FIG. 1 the blocks 11-14 are square in shape. However rectangular forms or other deviations from the square form may be employed.

Each of the blocks 11-14 includes a roadway completely surrounding the block. For example block 11 includes a roadway having six individually labeled segments, the outer peripheral segments 21 and 22 and the interior segments 23 through 26. Blocks 12, 13 and 14 have similarly identified roadway segments 31-36, 41-46 and 51-56 surrounding each block, respectively.

Each of the roadways has a width suflicient to accommodate two lanes of traffic moving in opposite directions.

The center of each lane of trafiic is represented by the broken lines in FIG. 1.

Four crossover devices, 61 through 64 are constructed along the interior roadways of the matrix in FIG. 1. The purpose of these crossover devices is to switch the traffic in adjacent pairs of interior roadways so that the trafiic moving about one block crosses over and begins moving about another block. For example the traffic. moving about block 11 on segment 26 crosses over to segment 45 and begins moving about the block 13. In a like manner traffic moving about block 13 on segment 46 crosses over to segment 25 where the vehicle begins traveling about the block 11. A mall 66 is shown in the center of the matrix providing a dividing strip between the interior roadways. It may be seen that no traffic flows across the center of the matrix where the mall 66 exists.

Four traffic lights 71-74 are located at the outer corners of the matrix and four traffic lights 75-78 are located at the crossover points on the interior of the matrix. The traffic lights are synchronized so that vehicles entering the corners of the matrix travel without delay to the opposite corner of the matrix. For example vehicles entering at the corner of the matrix marked A leave the matrix at the corner marked C. In a like manner vehicles entering the matrix at the corner marked B leave the matrix at the corner marked D. Vehicles entering at C leave at A, while vehicles entering at D leave at B. In the diagram of FIG. 1 where the blocks are square, the crossover points 61-64 are located one third of the distance from the outer edge of the matrix, so that the distance between all traffic lights is equal.

In order to illustrate the direction of travel of the vehicles through the matrix, the two paths from A to C are now described. Vehicles entering the matrix at A are divided into two platoons by the traffic light 71 in a manner to be described below. The first platoon is directed into the segment 22. The arrows show the path followed by the first platoon through segments 22 and 23. The first platoon crosses over point 61 into segment 34. The first platoon continues along segments 34 and 35, through crossover 62 to segments 56 and 51.

The second platoon of traflic entering at A follows the path indicated by the arrows in segments 21, 26, 45, 44, 53 and 52.

The length of travel of the first and second platoons through the matrix is identical so that the first and second platoons may unite at the corner C to reform into a continuous stream of traffic.

Once having described the two paths through the matrix from A to C it is apparent that the paths followed by streams of trafiic from B to D, C to A, and D to B are analogous. This follows directly from the symmetry of the matrix.

In operation streams of traffic entering the matrix from all four corners are permitted to pass through the matrix shown in FIG. 1 without delay, :and without interference at the crossover points 61-64, due to the design of the road network and due to the synchronization of the traffic lights 71-78. The road network is constructed so that the overall length of segments 22 and 23 is equal to the overall length of segments 34 and 35, which in turn is equal to the overall length of segments 56 and 51. Therefore the time taken for a vehicle traveling at constant speed to move between any two of the trafiic lights 71-78 is equal. Accordingly the traffic lights may be synchronized so that the lights turn green as vehicles approach permitting them to pass without delay. Further, the arrangement of roadways in FIG. 1 permits the traffic to be divided into platoons which travel along predetermined segments of the roadways so that each platoon arrives at the crossover tratfic lights 75-78 during an interval of time when there are no vehicles arriving in the cross direction.

To illustrate this consider two continuous streams of traffic arriving at the corners A and B of the matrix in FIG. 1. A first platoon of trafiic is guided by light 71 so that segments 22 and 23 are filled with vehicles. At the same time light 72 fills segments 31 and 36 with vehicles from the stream at B. As the first platoon from A and the first platoon from B pass through lights 76 and 77 respectively, a second platoon from A fills segments 21 and 26 and a second platoon from B fills segments 32 and 33. Therefore after the first platoon from B has completely passed through light 77 and filled segments 55 and 54, the second platoon from A is free to pass through light 75 to fill segments 45 and 44. One may continue to observe the progress of the first and second platoons of the streams of traffic entering at A and B and determine that no interference occurs between the various platoons at any of the traffic lights provided the constant speed is maintained by the vehicles throughout.

Additional platoons of trafiic may enter the matrix at A and B, by alternately filling first the segments 22, 23, 31 and 36 and then the segments 21, 26, 32 and 33.

Having described above the interleaving of platoons of traffic entering the matrix at A and B, it is apparent that streams of traffic entering the matrix at C and D may be interleaved in the same manner due to the symmetry of the matrix. Further it may be seen that streams of traffic can enter the matrix at all four corners A-D at the same time. This is achieved by providing for two-way trafiic on each of the roadways. The synchronization between traflic lights 71-78 permits tratfic to flow in two opposing directions.

FIG. 2 illustrates one example of apparatus which may be used to synchronize the traffic lights 71-78. A traffic light 80 illustrates the details of traffic lights 71-74 in FIG. 1. The light 80 includes three sides 81-83 which are pivoted in FIG. 2 into a substantially single plane to facilitate illustration. The orientation of these three sides with respect to the roadways in FIG. 1 is illustrated by the U-shaped traffic lights 71-74 in FIG. 1.

Trafiic light in FIG. 2 illustrates the details of trafiic lights 75-78 in FIG. 1. Trafiic light 90 includes four sides two of which, 91 and 92, are shown in FIG. 2. The opposite sides are identical. The faces of the trafiic light 90 are identified in FIGS. 1 and 2 with the numbers 161 and 292 so that the orientation of the light 90 can be shown with respect to the roadways in FIG. 1. The three sides of the traffic light 80 each include three indicator lights designated 101-103, 104- 106, and 107-109 respectively and have symbols located therein. The light 90 has four sides, opposite sides being identical. The lights on one pair of oppos-ite sides are designated 110-112 and those on the remaining sides are designated 113-115. The symbol GT represents a green light permitting traffic to move straight ahead. The symbols G and G permit right and left turns respectively. Traflic is stopped when the symbol R (red) is illuminated. The symbol A corresponds to the conventional amber warning light.

Each of the indicators 101-115 is supplied with illuminating current through lines connected to four switches 121-124. The switches are operated by cams 131-1'34. Each of the cams is mounted upon a single shaft 135 which rotates at a constant angular speed in the counter-clockwise direction. Rotation of the shaft 135 may be accomplished by any well known motivating means. One revolution of the shaft 135 may be arranged to occupy an interval of two minutes, for example.

Cam 131 is provided with a lobe 141 which closes the switch 121 for a period of one minute, half of the two minute interval for a complete revolution of shaft 135. Considering the beginning of the cycle to be when the cams are in the position as shown in FIG. 2, the switch 121 is closed during the first minute of the cycle. Cam 132 is provided with a lobe 142 which closes switch 122 for one minute during the second half of the cycle. Cams 133 and 134 are provided with small lobes 143 and 144 respectively. Lobe 143 closes the switch 123 during a short interval just prior to the end of the two minute cycle. Lobe 144 closes switch 124 for a short interval just prior to the end of the first minute of the cycle.

Cams 133 and 134 operate the caution indicators (A). For example indicator 108 is connected via line to switch 124. When the switch 124 closes power is supplied from a power source 151 which is connected to all of the switches 121-124. The power source illuminates the indicator 108.

Indicator 102 is connected to both of the switches 123 and 124 via a line 152. Therefore power is supplied when either of the switches 123 or 124 close.

In a like manner all of the indicators shown in FIG. 2 are connected to switches 121-124 which illuminate the lights in a synchronized fashion. A waveform diagram is shown in FIG. 3 which illustrates the times during which the indicators are illuminated. Corresponding numbers are applied to the indicators 101-115 in FIGS. 2 and 3. The beginning of the cycle is indicated by the 0 on the left of the waveforms. The middle of the cycle is indicated by the broken line having the designation 1st minute, and the end of the cycle is indicated by the broken line on the right having the designation 2nd minute.

When the waveforms are at the upper level the associated indicator is illuminated. For example indicator 101 is illuminated during the first minute of the cycle as shown by a waveform 160 in FIG. 3. Those sides of the traffic light 90 which are not shown in FIG. 2 include indicators which operate in synchronism with the indicators on their opposite face. For example indicators 110-112 operate in synchronism with the indicators on the side opposite to side 91. It can be seen by inspecting the waveforms in FIG. 3 that traffic approaching lights 75- 78 are alternately permitted to pass so that no two vehicles can collide. This is readily seen by observing the waveforms next to indicators 112 and 115. Indicator 112 permits trafiic to flow during the first minute of the cycle while indicator 115 permits traffic to flow during the second minute of the cycle. Also indicator 110 stops traffic during the second minute of the cycle when indicator 115 is illuminated while indicator 113 stops trafiic in the opposite direction when indicator 112 is illuminated.

Indicators 111 and 114 perform the conventional function of providing a caution light during the last portion of the interval when traffic is permitted to flow through the crossover points 61-64.

Indicators 101-103 face the trafiic approaching the matrix at the corners A through D in FIG. 1. As shown by the waveforms in FIG. 3 adjacent to indicators 101-103 the incoming traffic is divided into two platoons. The first platoon includes cars arriving at the corners of the matrix during the first minute which are directed straight ahead. In the matrix of FIG. 1 the platoons at the four corners A through D moving straight ahead create a traffic pattern in the clockwise direction about the periphery of the matrix. During the next minute, or second half of the cycle, the vehicles approaching the matrix are guided to the right by indicator 103. This creates a counter-clockwise rotation of trafiic about the periphery of the matrix. It can be seen that the effect of the traffic lights 71-74- in FIG. 1 is to alternately direct trafiic in a clockwise direction for one half of the cycle and then in a counter-clockwise direction during the second half of the cycle. In this manner platoons will arrive at the cross-over points 61-64 in a synchronized fashion so that a crossover can be effected without interference from vehicles which are members of other platoons.

Indicators 104-109 and the waveforms adjacent thereto in FIG. 3 illustrate the manner in which the platoons are united again to form a continuous stream of outgoing traflic at the corners -A through D of the matrix shown in FIG. 1. During the first minute indicator 109 is illuminated permitting trafiic to flow straight out of the matrix. For example considering traffic light 71 in FIG. 1, indicator 109 faces the traffic on segment 22 which is moving out of the matrix. During the first minute any trafiic which is moving upward on segment 21 is faced with the indicator 104 (red) which is illuminated. During the second minute of the cycle indicator 106 is illuminated permitting traffic moving upward on segment 21 to make a left turn and leave the matrix. Also during this second minute in the cycle indicator 107 (red) is illuminated stopping any vehicles in segment 22 moving toward the left. At this point it may be noted that if the vehicles all travel at the same speed and no stragglers lag behind there should be no stoppage due to the illumination of the indicator 107. However in order to avoid a collision indicators such as 107 are provided to permit variations in speed without causing a subsequent collision.

Since the opposite faces of traffic light in FIG. 2 are operated in synchronism, two-way traffic is permitted to flow simultaneously through the crossover points 61-64. Two-way trafiic is also permitted to flow past traffic lights 71-74. This may be seen by observing the indicators 101 and 109 and the waveforms adjacent thereto in FIG. 3. Both indicators 101 and 109 are illuminated at the same time permitting two-way trafiic to flow in segments 22, 31, 52 and 41. During the second minute of the cycle indicators 103 and 106 are illuminated permitting two-way traffic to flow in segments 21, 32, 51 and 42.

To summarize the operation of the network of roadways in FIG. 1 the path of traffic from corner A to corner C is now described with reference to the waveforms in FIG. 3. During the first minute of the cycle, trafiic approaching the matrix at corner A is guided into segments 22 and 23. To make maximum use of the network of roadways the light cycle should be timed taking into account the speed of the vehicles and the distance between lights, so that the first vehicle passing through traflic light 71 arrives at traffic light 7 6 just as the second half of the cycle begins. Indicator 103 is illuminated during the second half of the cycle guiding trafiic into segments 21 and 26.

Also during the second half of the cycle indicator is illuminated permitting the first platoon of traffic to pass through crossover 61 into segments 34 and 35. The next phase of the cycle is the same as the first half of the cycle shown in FIG. 3. Therefore the first platoon is permitted to pass through the crossover 62 since indicator 112 is illuminated during this interval. At the same time the second platoon faces indicator 112 included within the traffic light 75, thereby permitting the second platoon to advance into segments 45 and 44. During the next cycle which is represented by the second half of the waveforms illustrated in FIG. 3, the first platoon is permitted to make a left turn at traffic light 73. During this same interval of time indicator 115 is illuminated at light 78 permitting the second platoon to advance into segments 52 and 53.

The next interval is represented by the first half of the waveforms in FIG. 3 during which time indicator 109 is illuminated permitting the second platoon to fall in behind the first platoon and pass out of the matrix at corner C.

Due to the four-fold symmetry of the network about an axis through the center of the mall 66 and normal to the plane of the matrix shown in FIG. 1, streams of traffic entering the matrix at corners B, C and D flow through the matrix in a manner identical to the traffic flow described above. No interference between platoons occurs due to the alternately spaced arrivals of platoons from different streams of traffic.

Although the specific embodiment as shown in FIG. 1 includesfour crossover traffic lights 75-78, the lights are not needed where proper speeds are maintained by the vehicles. Their function is merely to insure that no Vehicles lagging behind a platoon enter the crossover point during the time when another platoon should be passing through. Other means could be employed to prevent collisions, such as yield signs, caution lights, or the like. Further, the amber light is shown to overlap the trailing portion of the green light. Adjustment of the cam surfaces could be made so that the green light turns off when the amber light begins.

Another modification can be made in the design of the crossover devices 61-64. As shown in FIG. 1 a mall 66 divides the interior roadways. However, where a sufiiciently wide roadway exists to accommodate all of the lanes of trafiic, guide lines could be painted on the street to separate the traffic and to direct the flow of the roadways through crossover points.

Additionally, although the blocks 11-14 are shown as squares in FIG. 1, other variations in geometry could be employed. A rectangular geometry having one side longer than the other would cause unequal paths for platoons of trafiic divided from the same stream of incoming traffic. Therefore the platoon traveling the shorter distance would arrive at the next trafiic light before the other platoon. Since the lights must operate in synchronism, the early platoon would have to be delayed. In some applications of the present invention it might be preferable to permit these delays rather than reconstruct the blocks in the shape of squares.

Still another variation of the specific embodiment shown in FIG. 1 could be made where there are a large number of blocks available. Here each of the blocks 11-14 as shown in FIG. 1 could include a number of smaller blocks.

While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. The method of passing continuous crossing streams of trafiic through a four block matrix having roadways surrounding each block, comprising the steps of:

dividing each of the streams of traffic approaching the roadways on the outer periphery of the matrix into successive first and second platoons;

guiding said first platoons in a clockwise direction on the roads at the periphery of said matrix, and guiding said second platoons in a counter-clockwise direction;

interleaving and exchanging platoons from dilferent streams of trafiic on the roadways in the interior of the matrix; and

uniting the first and second platoons from the same stream of traffic emerging from the interior roadways of the matrix to form a continuous stream of trafiic. 2. The method of passing continuous crossing streams of traflic through an intersection including the roadways surrounding a four block matrix forming four pairs of adjacent interior roadways, and four peripheral roadways between the corners of the matrix and said interior roadways, comprising the steps of:

dividing each of the streams of tralfic approaching the corners of the matrix into first and second platoons of equal length;

guiding said first platoons in a clockwise direction about the peripheral roadways of the matrix, and guiding said second platoons in a counter-clockwise direc tion; interleaving and exchanging the platoons of traffic on said pairs of adjacent interior roadways; and

uniting the first and second platoons from the same stream of trafiic arriving at the corners of said matrix to form a continuous stream of traffic.

3. An intersection arranged to pass continuous crossing streams of trafiic through a four-block matrix comprising:

roadways surrounding each of said four blocks forming four pairs of adjacent interior roadways, and four peripheral roadways between the corners of the matrix and said interior roadways, said four pairs of interior roadways intersecting one another at the same level so that trafiic is switched from one interior roadway to the other adjacent interior roadway and vice versa; and

means for guiding trafiic approaching the corners of said matrix alternately in the clockwise direction about the peripheral roads of the matrix, and then in the counter-clockwise direction.

4. The method of passing continuous streams of traffic through an intersection including the roadways surrounding a four square block matrix forming four pairs of adjacent interior roadways, and four peripheral roadways between the corners of the matrix and said interior roadways, comprising the steps of dividing each of the streams of traffic approaching the corners of the matrix into first and second platoons each having a length equal to one and one third times the length of the sides of said square blocks;

guiding said first platoons in a clockwise direction about the peripheral roads of the matrix and guiding said second platoons in a counter-clockwise direction;

interleaving and exchanging platoons of traffic on said pairs of adjacent interior roadways at points located one third of the distance from the outer periphery of the matrix to the center of the matrix; and

uniting the first and second platoons from the same stream of traffic at the corners of the matrix to form a continuous stream of traffic.

5. An intersection arranged to pass continuous streams of trafiic through a four block matrix, said blocks having the shape of a square, comprising:

roadways surrounding each of said four blocks forming four pairs of adjacent interior roadways, and four peripheral roadways between the corners of the matrix and said interior roadways, said four pairs of interior roadways intersecting at the same level so that tratfic is switched from one interior roadway to the other adjacent interior roadway and vice versa, the location of said intersections being one third of the distance from the peripheral roadways to the center of the matrix; and

control means for guiding trafiic approaching the corners of said matrix alternately in the clockwise direction about the peripheral roads of the matrix, and then in the counterclockwise direction.

6. An intersection as defined in claim 5 wherein said control means alternately guides the traffic so that equal platoons of trafiic are guided along the peripheral roadways, the lengths of said platoons of tratfic being one and one third times the length of the sides of said blocks.

7. In a trafiic control and roadway system controlling the flow of continuous streams of traffic through an intersection, the roadways of said intersection surrounding a four block matrix forming four pairs of adjacent interior roadways, and four peripheral roadways between the corners of the matrix and said interior roadways, the system comprising:

traffic controlling means located at the outer corners of the matrix for directing traffic approaching the corners of the matrix alternately in a clockwise direction about the peripheral roads of the matrix and then in a counter-clockwise direction; and

four additional trafiic controlling and guiding means each located along a different pair of interior roadways for directing and switching the traffic from one interior roadway to the other adjacent interior roadway and vice versa.

8. In a traffic control and roadway system controlling the flow of continuous streams of traffic through an intersection, the roadways of said intersection surrounding a four square block matrix forming four pairs of adjacent interior roadways, and four peripheral roadways between the corners of the matrix and said interior roadways, the system comprising:

a first group of four traflic controlling means located at the outer corners of the matrix for directing tratfic approaching the corners of the matrix alternately in a clockwise direction about the peripheral roads of the matrix and then in a counter-clockwise direction; and

a second group of four additional traffic controlling and guiding means each located along a ditferent pair of interior roadways for directing and switching the traffie from one interior roadway to the other adjacent interior roadway and vice versa, each of 9 10 said second group being located one third of the References Cited by the Examiner distance from the exterior roadways to the center of the matrix UNITED STATES PATENTS 9. In a trafiic control system as defined in claim 8 2,064,525 7/1952 Zannettos 340 40 wherein said first group of controlling means are adapted 5 2,758,293 8/1956 Hitchins 3404O to alternately guide the traffic so that two platoons of 2,949,067 8/1960 cedeno 4 1 trafiic are formed having lengths equal to one and one third times the length of the sides of said blocks.

10. In a traflic control system as defined in claim 9 wherein said first group and second group of traffic controlling means are operated in synchronism With each other.

CHARLES E. OCONNELL, Primary Examiner.

10 N. C. BYERS, Assistant Examiner. 

7. IN A TRAFFIC CONTROL AND ROADWAY SYSTEM CONTROLLING THE FLOW OF CONTINUOUS STREAMS OF TRAFFIC THROUGH AN INTERSECTION, THE ROADWAYS OF SAID INTERSECTION SURROUNDING A FOUR BLOCK MATRIX FORMING FOUR PAIRS OF ADJACENT INTERIOR ROADWAYS, AND FOUR PERIPHERAL ROADWAYS BETWEEN THE CORNERS OF THE MATRIX AND SAID INTERIOR ROADWAYS, THE SYSTEM COMPRISING: TRAFFIC CONTROLLING MEANS LOCATED AT THE OUTER CORNERS OF THE MATRIX FOR DIRECTING TRAFFIC APPROACHING THE CORNERS OF THE MATRIX ALTERNATELY IN A CLOCKWISE DIRECTION ABOUT THE PERIPHERAL ROADS OF THE MATRIX AND THEN IN A COUNTER-CLOCKWISE DIRECTION; AND FOUR ADDITIONAL TRAFFIC CONTROLLING AND GUIDING MEANS EACH LOCATED ALONG A DIFFERENT PAIR OF INTERIOR ROADWAYS FOR DIRECTING AND SWITCHING THE TRAFFIC FROM ONE INTERIOR ROADWAY TO THE OTHER ADJACENT INTERIOR ROADWAY AND VICE VERSA. 